Last night we took my car to the dyno to finish tuning it out. Dave Blundell (Blundar) is doing the tuning, and VERY well I might add. It was on a Mustang dyno so you generally go by the 15% correction factor for DynoJet numbers. Before I get into things, the setup is:

85x89mm
Eagle lightweight crank
12.7:1 compression
BASZ R head, full port and polish
Skunk2 Pro 1 cams
TWM 50mm ITBs
450cc injectors
HyTech header

We started with a baseline LOW CAM pull of 158whp, (181.7 on DynoJet). Everything was going great. When we started to go into high cam is when it started to get weird. The tuning was unresponsive to adding timing to the car, the numbers would actually drop off, but we could pull timing out and it would stay unresponsive, not go up nor down. The graph showed the cams pull to around 8500 (way too low IMO) and then it dropped like a rock, not gradual or anything just down. We played with the AFRs and cam timing as well and it was all useless it seemed. At the end of the night it yielded 204.7whp (235.4 DynoJet) with 10 degrees of timing being pulled out than before we came in. We started with 28 and ended up with 18 and also ended up with AFRs in the high 12's. Now we talked to a few people as to why the numbers could be falling so quickly and the said it could be caused by the MSD box frying the ignitor, I called Tbone last night and he also said this could be causing the sharp power drop. ANy suggestions here. We are currently building the MSD ignitor bypass circuit right now and are hitting the dyno again tomorrow afternoon. It baffles all of us why it would go down so bad when timing was added, something isn't adding up here. We used a local shop's dyno (Raceline) and the tuner there couldn't understand it either. I need some direction on what to look for here.


Modified by PandaHatch at 3:42 PM 9/30/2005

 

not so much the ignitor, the pickups in the distributor for crank and cam sensors can go bad and cause it to drop off early. but I don;t think you have that problem, some motors tend to drop off at 8500rpm.

did you check clearance between piston valve relief pocket and the valve while the big cam is open ?

 

Yea I did, it's not a gradual drop though is the thing, it's a rock. We are thinking it may be a reverse spark, especially up top in higher RPMs, especially with the power it made at lower RPMs in low cam.

 

The Pro1's do not make power after 8500, they should peak just before that. VTEC is around 5500 depending on header. There should be no blips in the HP curve.
Qustion 2 what spings and ret. and what was the installed height, seat pressure. It could be valve float.

 

Very interesting problem. Nothing I can add but I hope you find the problem and better response on the dyno

 

Vtec crossover smooth as butter at 5688.

Peak torque was 7500 RPM. ~160 ft/lbs if I remember right. Loses ~40 ft/lbs in 1000 RPM.

AFRs of 12.3-12.5 and 13.3-13.5 were tried. Leaner made more power. Brand new LSU4 sensor on PLXM300.

There are several reasons why I sincerely believe that there is an issue somewhere we haven't found:

1. The motor is running ~17 degrees total timing at peak torque. Little low perhaps?
2. The motor made more torque with timing at 14 degrees@8500 than 32 degrees@8500. It's responding to having timing YANKED not timing ADDED.
3. Timing values are just way too low! No motor I have ever tuned has behaved like this! I refuse to believe that this PR3 head and CP 12.5:1 85mm bore pistons are "just that efficient"

I've talked to about half a dozen tuners at this point, and so far some of the best suggestions have revolved around ignition issues. Sean Powers suggested that the MSD box might be triggering on the wrong edge of the ignition output. I believe the white trigger is currently wired off the gnd side of coil, but that would open up the possibility for a marginal/failing ignitor to give issues...

I had Brian pick up the parts for the ignitor bypass circuit and we're gonna try to trigger the 6AL directly off the ignition output bypassing the ignitor. If that doesn't work out, gonna try a bone stock honda B16 dizzy and hope for the best there.

Compression excellent.
Leakdown excellent.
Cam-cam and cam-crank aligned properly
0 - +4 on intake cam tried +2 to +3 were about equal, 0/+1/+4 all lost a little.
0, +2 on exhaust cam tried. +2 lost power and then ran out of time.
NGK 9-series plugs, heatmark excellent, no pepper or flakes.
New MSD plug wires

I don't ******* get it. Less cam on stock heads has carried power out further - I know the Pro1s aren't designed to rev to 12K, but 8200 RPM HP peak? that's lower than a set of CTR cams!

 

The source himself, I don't get it either Dave.

 

Oh yeah, Brian. tony1 suggested putting an oil pressure guage on the car if you don't have one already. A brand new motor that he was tuning was falling flat on it's face on the top end. There was enough oil pressure to activate vtec, but not enough to keep it going. I think I have an old jank 50mm autometer guage you can borrow.

 

I've always had one on there, haven't you nticed it? Get's 80+psi in VTEC usually around 85psi.

 

I haven't been smoking any weed this week so you can't make stoner jokes. I'm just blind...

 

i'm no expert here, but i did see 2 or 3 things that caught my eye (things that i have read on this forum over the past year)

high compression motor - what octane are you using? 9-range spark plugs? possibly too hot for such high compression? (i have posted several time regarding heat ranges and have not gotten a solid answer - some people say hi-comp/all motor setups require cooler plugs, some say hotter, i dont know yet!) also timing in relation to compression - some of the posts i have studied suggest that with high compression, you do want to retard the timing a bit....which would explain why there was more power with the more retarded timing....i dunno - i'm subscribing for educational purposes.

 

We're in the process of making an ignitor bypass as I type this and also going to try a stock distributor. I'll keep everyone updated.

 

My last ITB setup also did better with timing retard instead of advance. I was thinking that the fuel had more time to atomize before the spark and it was getting more complete combustion this way, but I didn't have dyno access to test the theory before I sold the car. Try advancing the dizzy, and then retarding the ignition timing a bit further in the ECU. This should cause the injectors to fire sooner. Again, I never had the chance to test this.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Kendall &raquo;</TD></TR><TR><TD CLASS="quote">Try advancing the dizzy, and then retarding the ignition timing a bit further in the ECU.</TD></TR></TABLE>

good tip. i did something similar with the fuel maps on my setup. i was running rich at 30psi (fuel not boost) on a jdm p30 map. i switched to an edm p30 map and adjusted for 330cc injectors and that map was much leaner. i was able to get a near perfect afr at 47psi with that map.

so the same theory above applied, advance the dizzy but retard the ignition maps, just might do the trick.

 

What kind of fuel pump are u using? may have a faulty injector. I know you can get a 12.3-12.5 and 13.3-13.5 reading with bad spark in one cylinder I dont see why the same couldnt be for cloged or faulty injector.

bad spark not enough fuel burns
bad injector to much or not enough fuel to burn

 

As I run a stand alone ECU I can only say total timing should be 32-33 above 7500 and 30 total 6000-7500. The Pro1's will run to 9000 but that is not their best range. Sounds like a spark problem or spring problem.

 

The valvetrain setup is Ferrea Endurance springs, give a seat pressure of 80lbs. We're gonna see what happens tomorrow guys.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PandaHatch &raquo;</TD></TR><TR><TD CLASS="quote">I've always had one on there, haven't you nticed it? Get's 80+psi in VTEC usually around 85psi. </TD></TR></TABLE>

i thought oil psi should be close to 100psi? maybe i'm wrong, anyways...good luck and hope you find the problem, because i had a gsr motor, 81.5mm bore with 12:1cr, pnp head, and buddy club spec 4's, and i peaked 175whp@7900rpms...anyways i never found out what was wrong...maybe it was my tuner too...cuz he didnt add any timing after vtec...meaning it stayed at around 18degrees or something...there are som really shitty tuners out there *cough*CARBCONN*cough*...hahaha...anyways good look in finding out the problem.

 

maybe the cams cant flow enough for that setup...just a thought....and ive seen quite a few motors make more power on the top end with timing pulled....so who knows

 

Get some Skunk2 stg 3's or pro 2's..maybe that would help, i dunno just a thought

 

Another thought after reading the above post. Pretty much every ITB equipped motor I've dealt with was happier when overcammed as opposed to undercammed.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by reddohcvtec &raquo;</TD></TR><TR><TD CLASS="quote">Get some Skunk2 stg 3's or pro 2's..maybe that would help, i dunno just a thought</TD></TR></TABLE>

skunk2 stg2 after seeing dyno charts ccompared to the pro2's....but the skunk2 stg3 cams are nice

 

So you think that I may actually be undercammed? Interesting, I'll run that by Dave tomorrow when we hit the dyno again.

 

honestly if you arent experiencing missfires then i would assume the ignition is fine...ive been running the msd sci with blaster coil for years with no problem.... i would assume your undercammed....if anyone else has input please lets hear it

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2k.civic.si &raquo;</TD></TR><TR><TD CLASS="quote">

skunk2 stg2 after seeing dyno charts ccompared to the pro2's....but the skunk2 stg3 cams are nice</TD></TR></TABLE>

are you referring to the 11.1 1.8 motor dyno?